1. Field of the Invention
An exemplary preferred embodiment of the disclosure relates to a spindle motor for a disk drive apparatus.
2. Description of the Related Art
A disk drive apparatus such as a hard disk drive apparatus has been required to control, for example, the rotation of a disk and the movement of a head more accurately with an increase in recording density of a disk. A hard disk drive (HDD) has an interior space filled with a low-density gas such as helium or hydrogen to reduce resistance to be applied to a disk and a head in rotating a spindle motor. This configuration reduces the vibrations of the disk and head and achieves highly accurate data recording.
One of known HDDs is equipped with a spindle motor (hereinafter, simply referred to as a “motor”) that includes a base defining a part of a housing of the HDD.
If the HDD is filled with helium or hydrogen of considerably small molecular weight, the gas is frequently leaked out of the housing through a clearance between members of the HDD. Consequently, the HDD has been required to seal the clearance, thereby preventing the passage of the gas more than before. The clearance is sealed with, for example, a rubber ball that prevents the passage of gas. However, the use of a sealing member made of an elastic material such as rubber raises a possibility in that a helium gas is leaked through a slight clearance between the sealing member and a through hole. In addition, the helium gas has a small particle size and therefore escapes to the outside through the rubber ball in some cases.